The present invention relates to a detection device, particularly for surface checking cigarettes.
The surface quality of cigarettes coming off a production machine is normally checked by feeding the cigarettes successively through a detecting and monitoring device of the type described in U.S. Pat. No. 4,639,592. This comprises four separate optical units, each designed to detect surface flaws of various types on a respective quarter of the lateral surface of the cigarette, and each presenting a light source for directing a light beam on to the respective lateral surface quarter of the cigarette.
The light rays reflected by each surface quarter are concentrated by the respective optical unit into a beam, which is sent to a respective monitoring unit normally comprising a telecamera. This produces an image, which is compared, inside the monitoring unit, with a specimen image, and, in the event any major discrepancies are detected between the two images, a signal is emitted for rejecting the cigarette.
Though widely used and reliable enough from the operating standpoint, a major drawback of known detection devices of the aforementioned type is the relatively high cost, mainly due to featuring four monitoring units.
Moreover, by virtue of each surface quarter of the cigarette requiring both a light source and an optical unit, known detection devices of the aforementioned type are also relatively cumbersome and, hence, difficult to accommodate, for example, on filter assembly machines.